Dozens of parents and children gathered at a West Harlem elementary school yesterday, chanting, “Save our school!” to protest a Columbia University proposal to use a portion of the building for a new charter high school.

PS 36 on West 123rd Street could be split up by the university and the Board of Education to accommodate the Columbia Science, Math and Engineering School by next year.

Parents say their kids are too young to be mixing with high-school students.

“If they come in, our kids will have less space,” said Kim Wynn, president of the Parents Association.

“This is a great school, we don’t want it to change,” said parent Cedric Flemming.